1. Field of the Invention
The present invention relates to a power supply device for electric vehicle. More particularly, the invention relates to a power supply device for electric vehicle that is preferable for realizing an increased power supply capacity and an enhanced operability in mounting and detaching the power supply device to and from an electric vehicle, while securing a locking mechanism (lock mechanism).
2. Description of Background Art
Conventionally, in an electric vehicle, a battery pack having a plurality of battery cells assembled in a battery case are mounted as a power supply device. For instance, Japanese Patent Laid-open No. 2003-231493 describes a motorcycle wherein a battery pack is mounted on a battery holder attached to a vehicle body. More specifically, Japanese Patent Laid-open No. 2003-231493 describes a battery pack mounting structure and a lock mechanism wherein a groove part provided at an upper surface of the battery pack is provided with a hook part, and a mounting part fixed to a seat tube is provided with an engagement part for engagement with the hook part. The engagement part is movable inward and outward in the vertical direction. In the motorcycle described in Japanese Patent Laid-open No. 2003-231493, a handle to be utilized at the time of carrying the battery pack is provided at an upper portion of the battery pack so as to be located on the vehicle body rear side, or on the rear wheel side.
In the motorcycle described in Japanese Patent Laid-open No. 2003-231493, the handle provided on the battery pack is disposed in a narrow place between the mounting part projecting rearwardly from the seat tube and the rear wheel located just on the rear side of the battery pack. Therefore, there is little space around the handle. Accordingly, at the time of mounting or detaching the battery pack, a hand must be placed into and out of the narrow space between the mounting part and the rear wheel, which leads to poor operability.
In addition, the hook part to be engaged with the mounting part is provided on the battery pack body side, in other words, on the side of the battery case in which the battery cells are accommodated. Therefore, the volume for accommodating the battery cells is reduced, whereby battery capacity is limited.